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Brains Are a Mosaic of “Male” and “Female”? It’s Called Being Human

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A study published on Monday has caused a stir. The Washington Post describes the work:

Lots of folks — well-intentioned and otherwise — like to point out the supposed differences between male and female brains. But it’s time to throw away the brain gender binary, according to a study published Monday in the Proceedings of the National Academy of Sciences. Brains can’t really fit into the categories of “male” or “female” — their distinguishing features actually vary across a spectrum.

It’s exciting news for anyone who studies the brain — or gender. And it’s a step towards validating the experiences of those who live outside the gender binary.

That’s a bit of hype. The researchers don’t go so far. Here’s how they describe the significance of their work:

Our results demonstrate that regardless of the cause of observed sex/gender differences in brain and behavior (nature or nurture), human brains cannot be categorized into two distinct classes: male brain/female brain.

Nonetheless, there are things that need pointing out. Our brains are too complex to reduce gender differences to physical differences. And the underlying assumption is that our brains determine who we are.

The study found some physical characteristics that were typically male or female, and some that were shared between the sexes. There was no one physical characteristic that only males shared, or females shared. And they found that most individuals were a mosaic of male and female traits. This is the source of their claim that there are no distinct classes of male and female brain.

So what about this physical mosaicism of our brains? Their main point is that very few individuals had brains that were all female or all male. However, that does not invalidate earlier studies that found, on average and taken as a whole, male and female brains are different.

Besides their physical studies of the brain, they also point out that behaviors show the same mosaicism. Any given individual will have activities common to their sex, but some that differ. They call that internal inconsistency. I call it being human.

Our brains are each unique. We are each a mosaic of talents and preferences. He, an engineer, likes cooking, while she, a music teacher, likes remodeling. These activities may be classified as male or female, but really they are human, and people of either sex may like any of them. And none of these preferences are reducible to particular physical characteristics of the brain.

The implicit assumption behind this work, as I said, is that our brains determine who we are — that our wetware specifies our choices and behavior, or our gender. That’s a strictly materialistic point of view. There is more to us than neurons. The work of Mario Beauregard, Jeffrey Schwartz, and Thomas Nagel all indicate that our minds cannot be reduced to neurons firing. Rather, there is something called the mind that experiences the world through the brain but that influences the brain by its activity. Indeed, the mind, by changing thinking patterns, can even restructure neural pathways.

Might we not think of ourselves as a mosaic of choices made over the years, choices that have brought us to now? Our inclinations and our upbringing have an effect, to be sure, but it is still what we choose to do with those experiences that make us who we are today. I love music but opted to study biology. If I had chosen music my life would have been very different, and that set of experiences would have shaped me into a different person, at the same time shaping my brain.

In the end, it’s a question of free will versus determinism. A person can choose to do a thing that goes against his desires. Or not.

Image: � rocketclips / Dollar Photo Club.

Ann Gauger

Senior Fellow, Center for Science and Culture
Dr. Ann Gauger is Director of Science Communication and a Senior Fellow at the Discovery Institute Center for Science and Culture, and Senior Research Scientist at the Biologic Institute in Seattle, Washington. She received her Bachelor's degree from MIT and her Ph.D. from the University of Washington Department of Zoology. She held a postdoctoral fellowship at Harvard University, where her work was on the molecular motor kinesin.